Short answer: thicker tiles are usually stronger and better suited to floors and outdoor use, but thickness alone doesn’t tell you a tile is high quality. Material, density, water absorption and the PEI wear rating matter more than the millimetre count on the side of the box. Here’s how to read tile thickness properly before you buy.
What tile thicknesses actually mean
Australian tiles broadly fall into three thickness bands, and each band is built for a different job:
- 6-8 mm: wall tiles, splashbacks, light decorative work. Lighter to handle, easier to cut, but not rated for foot traffic.
- 8-12 mm: the standard band for residential floor tiles in kitchens, bathrooms, hallways and living areas. Most porcelain and ceramic floor tiles sit here.
- 20 mm-plus: outdoor pavers, alfresco areas, pool surrounds and driveways. Built to take impact, frost cycles and the weight of furniture or vehicles.
If a supplier is offering 6 mm tiles for a kitchen floor, they’re the wrong tile for the job — regardless of price.
Why thickness matters less than you’d think
A 9 mm full-body porcelain tile will outlast a 12 mm low-grade ceramic every time. The reasons sit further down the spec sheet:
Material and density
Porcelain is fired hotter and denser than standard ceramic. It absorbs less than 0.5% water (ceramic absorbs 3-7%), which is what makes it the right pick for wet areas and outdoor zones. Natural stone is a different category again — beautiful, but porous and softer than porcelain, and it needs sealing.
PEI wear rating
The PEI scale runs from 1 to 5 and rates how a glazed tile holds up under foot traffic. PEI 1-2 is wall-only. PEI 3 suits residential floors. PEI 4 covers heavy residential and light commercial. PEI 5 is full commercial. A thick tile with a PEI 2 rating is still a wall tile.
Breaking strength
Tested in newtons or pounds-force per the AS 4459/ISO 10545 standard. A dense 9 mm porcelain can have a higher breaking strength than a soft 12 mm ceramic. If a tile is going on a floor, ask the supplier for the breaking-strength figure rather than relying on thickness alone.
Where thickness genuinely matters
- Outdoor and pool areas. 20 mm pavers handle the weight of outdoor furniture, vehicles on a driveway, and the freeze-thaw cycle in colder Australian regions.
- Heated subfloors. Thinner tiles transmit heat faster, so 8-9 mm is the typical pick over electric underfloor heating.
- Tile-on-tile installs. If you’re laying over an existing floor, a thinner tile keeps the door clearance and the threshold transitions usable.
- Heavy commercial loads. Warehouses, workshops and showrooms need thicker, denser tiles with a high breaking strength.
Subfloor and installation trade-offs
Thicker tiles are heavier and need a flatter subfloor. Lippage — where one tile edge sits proud of the next — is more obvious on thick large-format tiles, so the slab usually needs self-levelling first. Thinner tiles are more forgiving on minor subfloor irregularities but offer less impact resistance once down. Either way, larger tiles (600×600 and up) need levelling clips during install regardless of thickness.
Thicker, larger and stone tiles also push the labour rate up. We’ve broken down what tilers charge by tile type in the tiler rates per m² in Australia guide.
What to ask before you buy
- What’s the tile rated for — wall, residential floor, commercial, or outdoor?
- What’s the PEI rating and the water absorption percentage?
- Is it full-body porcelain, glazed porcelain, or ceramic?
- What’s the breaking strength in newtons?
- What thickness does the supplier recommend for your specific room and subfloor?
If a salesperson can’t answer those without checking the box, that’s a flag.
Bottom line
For a standard residential floor in Australia, an 8-10 mm porcelain tile with a PEI 3 or 4 rating is the sweet spot. Push to 20 mm pavers outdoors, drop to 6-8 mm for walls, and check the PEI and water-absorption figures rather than treating thickness as a proxy for quality. If you’re weighing tiles against alternatives for a kitchen or wet area, our best flooring for kitchens and waterproof flooring options guides cover where tiles win and where hybrid or vinyl makes more sense.
Ready to shop? Browse our full tile range online, or drop into our Sydney or Brisbane showroom to see the range in person.